The page "How to Write Buffer Plugin" does not have any content

### Describe the bug

The page [https://docs.fluentd.org/plugin-development/api-plugin-buffer](https://docs.fluentd.org/plugin-development/api-plugin-buffer) does not have any relevant content.

### Link to the problematic documentation

https://docs.fluentd.org/plugin-development/api-plugin-buffer

### Expected explanation

I expected to see information about how to write a buffer plugin

### Additional context

I'm interested in writing a new buffer plugin for the Redis service